Facts and fiction about food and cooking, by Peter Aitken
Pressure cookers work because they allow you to cook food in water or steam above the usual boiling point of 100 degrees C (212 F). Under pressure that is higher than normal, water boils at higher temperatures, and these higher temperatures cook your food faster and, sometimes, better. But, how much extra pressure—that’s the question.
At normal atmospheric pressure, water boils at 100 degrees C (212 degrees F). If your pressure cooker raises the pressure by 7 PSI (pounds per square inch), the temperature goes up to 112 degrees C. An increase of 15 PSI gives you 120 degrees, and a 37 PSI increase in pressure gives you 140 degrees C. The higher the pressure, the faster your food will cook. There’s no practical way to measure the pressure in your cooker, so, be warned: the timing in pressure cooker recipes may need to be modified based on the characteristics of your cooker. After a few tries, you should be able to get a feel for whether your cooker is faster or slower than typical.
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